Sgt Lumpy, profile much?
West Palm Beach police, back in the 80's, would routinely stop drivers for DWB (Driving While Black), to see if they had work permits for the island.
In your scenario, aside from looking different and openly carrying, what exactly is the gang-banger looking dude doing that merits a call to the police, let alone a stop and interview?
If he's acting as though he's casing houses; if he's scowling at little old ladies and making them get off the sidewalk; if he's yelling threats at people; if he's urinating in your bushes; then a call and a stop are in order.
Looking different, and carrying? Not valid reasons for the call, let alone the stop.
If somebody can't articulate an actual crime that appears to be in progress, or reason to suspect a crime is being planned, then what are you suggesting?